I made the same choice.
I won't call it an error. I knew going in that buying stock based on a drug trial is riskier than blackjack. It's more like betting the hardway numbers in craps or double zero in roulette. I've lost a bundle on this, not to mention a lot of hope and belief.
Anytime I buy a stock, I gotta know if there is an emotional tie to the thing I'm buying. If so, I don't buy it -- OR -- I need to know that I'm taking a substantial risk because my closeness to the concept is likely to cloud my thinking. I trade market indexes, puts, calls and shorts. But, I could not get my feelings about MS out of the way in order to be objective about this stock. This one is done, not much we can do now except hold it through the CPR period. If you've lost more than $3,000 - chat with the person who does your taxes NOW and get advice. King Paulson will share some of your loss with you.
Going forward, please don't be discouraged about investing. It's easy to be right now. But, it's exactly these sorts of times when the best opportunities come along. Yes, we are due for another market crash before the economy gets going again. But, that's like getting a 50% off coupon from Kohl's. One day we'll look back and say, OMG, there was once a great chance to buy Pepsi, McDonalds and Walmart for about $50.
Never lose hope.